Optimal RT regimen for PCI in LS SCLC

Also in the Lancet Oncology this week:

The PCI collaborative group (RTOG, EORTC, &others), published their results in a randomization between three different PCI doses and schedules for patients with LS-SCLC.

720 patients with limited stage SCLC and complete response to thoracic RT with concurrent chemotherapy were randomized to:
1. 25Gy in 2.5Gy QD x 10
2. 36Gy in 2Gy QD x 18 or 1.5Gy BID x 24.

2-year incidence of brain metastases was 29% (95% CI 24–35) with 25Gy and 23% (18–29) with 36Gy (HR 0.80 [95% CI 0.57–1.11], p=0.18).

2-year OS was 42% (95% CI 37–48) with 25Gy and 37% (32–42) with 35Gy (HR 1.20 [1.00–1.44]; p=0.05). Deaths in the 35Gy seem to have been cancer related. Five serious adverse events occurred in the standard-dose group versus zero in the higher-dose group. Acute fatigue seen in 30% with 25Gy vs 34% with 35Gy, headache in 24% vs 28%, and nausea or vomiting 23% vs 28%.

Their conclusions were that 25Gy in 10 results in equivalent brain control and superior survival.

One comment that I would add to this is that brain mets did trend towards an improvement with higher dose, and that the deaths in the high dose arm are difficult to ascribe directly to the intervention. It is also interesting that there were more serious adverse event in the low dose arm, perhaps reflecting the larger dose per fraction? That said, the results are the results, and this trial should help us in PCI regimen selection.